L1 Body fluids and Oedema Flashcards
Percentage of water in a standard 70kg man
60%
State the body compartments where fluids accumulate
Intracellular and extracellular
Compare and contrast water balance in males and females [and in early life and in older populations]
Men have greater total body water percentage than females. Older people also have a lower TBW due to muscle wastage. NB muscle holds most of the water. Infants hold the greater TBW than at any other stage
Outline the differences between dehydration and water toxicity
Dehydration is when the cells doesn’t have enough water so absorb water from the extracelular matrix, other cells, tissues and organs. Sacrificing cells in the process. Water toxicity is when the body has too much water within it and so hyponatraemia takes place ie low salt conc outside cell. so cells swell and burst. Leads to metabolic failure and cell, tissue and organism death
Explain the concepts behind positive and negative feedback loops
Positive feedback loop is when an intiator stimulates an effector to continue producing more of the initiator, however a negative feedback loop is when the intiators presence inhibits the effector so it reduces its production of the initiator
Explain the importance of acid-base balance for normal human physiology
pH alters shape of enzyme and therefore the denatured enzyme stop performing biochemical function and so biochemical processes stopped
State the ‘normal range’ for pH in tissues including blood
7.35-7.45
State the ‘normal range’ for core body temperature
36.5’C -37.5’C
State the mechanisms that regulate pH
If acidosis occurs, increase of the respiratory rate. In the long term the kidney excrete the H+ and retain bicarbonate (HCO3-) . If alkylosis occurs, breathe into a paper bag. In the long term the kidneys remove the HCO3- out of the blood and retain the H+. NB: acidosis may occur due to hyperventilation and so breathe out more than in so CO2 lost and so blood is alkaline
State the mechanism that regulate temperature
When the hypothalamus and/or skin receptors detect an increase/decrease from the set point the corresponding mechanisms are initiated. if the body is too hot, vasodilation, pilorelaxation and sweating. If the body is too cold, vasoconstriction, piloerection and shivering. Also behavioural changes take place ie stretching or curling up
Where does the water end up ?
1/3 of TBW is extracellular fluid, of which 1/5 is plasma and 4/5 is interstial fluid and 2/3 is intracellular fluid
What is osmolality?
function of the concentration of particles in solution (milliOsmoles mOsm/kg), solutes that ionise have 2mOsm/kg per millimole whereas others have 1 mOsm/kg per millimole
CLINICAL Describe the process of oedema
“Fluid build up in the interstitial space. When hydrostatic pressure (of blood vessels) > osmotic pressure (interstitial fluid) Can be caused by plasma proteins in the interstitial space or the lymphatics system being blocked or damaged
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Describe the importance of the hypothalamus in homeostasis (11)
Deals with thermoregulation, plasma osmalality, heart rate, blood pressure, feeding, satiety (feeling full), regulation of GI tract, circadian rhythms, stimuli from autonomic nervous system, emotion and lactation.
Define the term homeostasis
Process by which the cell,tissues and organism maintain its internal environment/ correct physiological range.
